A conventional variable resisters is disclosed in Japanese Utility Model Laid Open Print No. 1-95602 published without examination on Jun. 23, 1989. In this conventional variable resister, one end portion of a resistive element is electrically connected to an elastic end portion of a terminal to which electric current is applied from an exterior power source. The elastic end portion is formed in such a manner that one end portion of the terminal which is in the form of a metal or steel plate is curved into a quasicircular configuration. A similar type of structure is also disclosed in German Offenlegungsschrift No. 195 18 340 A1 published on Nov. 30, 1995.
In these types of conventional resisters, because one end portion of the terminal is in elastic engagement with the resistive element, the electric connection between the resistive element and the terminal is in the form of a line-to-surface contact. Thus, the electrical conductivity between the resistive element and the terminal becomes unstable when the device is mounted on an automotive vehicle body which is subject to vibration.
In addition, the foregoing curved structure or configuration of the terminal makes the spring constant of the curved end portion large and the elastic range of the curved end portion small. Thus, if one end portion of the steel terminal is curved excessively, the resultant end portion is of insufficient elasticity. Consequently, in extreme cases, it may not be possible to establish electrical contact between the terminal and the resistive element.